1. Field of the Invention
This invention relates to a variable optical-property element such as a variable mirror, a variable focal-length lens, a variable focal-length diffraction optical element, or a variable deflection-angle prism, and to an optical apparatus such as a digital camera, a TV camera, an endoscope, spectacles, a video projector, a telescope, a camera finder, an imaging apparatus of a mobile phone (a digital camera or TV camera of a mobile phone), an optical information processor, or an optical interconnection apparatus, provided with an optical system including the variable optical-property element.
2. Description of Related Art
Conventional lenses have been manufactured by polishing glass, and focal lengths cannot be changed by the lenses themselves. Thus, for example, to carry out focusing of a camera or the magnification change of an optical system, lens units must be moved along the optical axis, and a mechanical structure becomes complicated.
Because a motor or the like is used to move a part of the lens units, this conventional practice has disadvantages that power consumption is large, noise is produced, response time is long, and much time is required for moving lenses.
For shake prevention as well, mechanical movement of the lenses by a motor or a solenoid causes defects such as large power consumption and a complicated mechanical structure, resulting in a higher cost.
In order to obviate these defects, lenses using variable mirrors are proposed, for example, in Japanese Patent Kokai Nos. 2000-298237, 2002-189173, 2002-233006, 2002-233007, 2003-29150, 2003-98435, 2003-233008, 2003-302578, 2003-77921, 2003-102219, and 2004-109694.